The present invention relates to a solid adhesive composition having an excellent applying performance even after an applying part of the solid adhesive is left to stand in the atmosphere for a long time.
Conventional solid adhesive compositions such as solid pastes have such a defect that if they are left in a cap-off state, the solvents evaporate, and the adhesive resins contained in the pastes are solidified on the surface layer of the applying part, so that the pastes are less liable to be applied when used next time.
In order to avoid this state, it has so far been tried to add scarcely-volatile solvents or change the composition of an adhesive resin, but the problem therewith is that a drying time for an applied paste is extended or the adhesive strength is lowered.
Disclosed in Japanese Patent Application Laid-Open No. Sho 53-42343 and Japanese Patent Application Laid-Open No. Sho 53-67739 are adhesive compositions suited particularly to flooring materials, for example, vinyl chloride-made tiles which are improved in an adhering workability by blending organic solvent solutions of vinyl acetate base polymers with glycerin monostearate, diglycerin monostearate and diglycerin distearate to extend open time (time spent until stuck together after applied and left uncovered) in Japanese Patent Application Laid-Open No. Sho 53-42343 and usable time (time spent until it becomes impossible to use adhesives from the time of preparing them) in Japanese Patent Application Laid-Open No. Sho 53-67739.
However, the adhesives disclosed in these official gazettes are adhesives of a solution type prepared by dissolving vinyl acetate base polymers in organic solvents.
On the other hand, disclosed in Japanese Patent Application Laid-Open No. Sho 61-293276 are solid pastes for office uses prepared by mixing 60 to 100 parts by weight of resins such as petroleum resins and natural resins with 100 parts by weight of waxes such as paraffin, stearic acid, carnauba wax and low molecular weight polyethylene wax using plasticizers such as dioctyl phthalate and dibutyl phthalate in combination therewith.
However, in the solid pastes for office uses disclosed in this official gazette, solvents and water are avoided being blended in order to remove a factor of losing the adhesive function caused by evaporation of the solvents and water. In addition thereto, it is positively disclosed that wax is used as a base material.
In light of the problems of the conventional techniques described above, the present invention intends to solve them, and an object of the present invention is to provide a solid adhesive composition having an excellent applying performance even after an applying part of the solid adhesive is left to stand in the atmosphere for a long time.
Intensive investigations of the problems on the conventional techniques described above repeated by the present inventors have resulted in finding that a solid adhesive composition meeting the object described above can be obtained by adding a specific substance to a solid adhesive composition containing at least an adhesive component, a gelling agent and a solvent, and the present invention has come to be completed.
That is, the solid adhesive composition of the present invention comprises the following items (1) to (8).
(1) A solid adhesive composition comprising at least an adhesive component, a gelling agent and a solvent, wherein contained in the above composition is at least one selected from the group consisting of waxes which are a solid at room temperature and have a solubility of 20% or less in the solvent at room temperature.
(2) A solid adhesive composition having an excellent cap-off performance, comprising at least an adhesive component, a gelling agent and a solvent, wherein contained in the above composition is a substance absorbing moisture contained at least in the atmosphere and/or the adhesive composition to form an evaporation-inhibiting film.
(3) A solid adhesive composition comprising at least an adhesive component, a gelling agent and a solvent, wherein contained in the above composition are at least one selected from the group consisting of waxes which are a solid at room temperature and have a solubility of 20% or less in the solvent at room temperature and a substance absorbing moisture contained at least in the atmosphere and/or the adhesive composition to form an evaporation-inhibiting film.
(4) The solid adhesive composition as described in the above item (1) or (3), wherein the waxes which are a solid at room temperature and have a solubility of 20% or less in the solvent at room temperature are at least one selected from the group consisting of paraffin waxes, olefin waxes, microcrystalline waxes, petrolatum, animal waxes, vegetable waxes, mineral waxes, polyethylene waxes and Fisher.Tropsch waxes.
(5) The solid adhesive composition as described in the above item (2) or (3), wherein the substance absorbing moisture contained at least in the atmosphere and/or the adhesive composition to form an evaporation-inhibiting film is at least one selected from the group consisting of glycerin fatty acid esters, polyglycerin fatty acid esters, alkyl phosphates, polyoxyalkylene fatty acid esters, sorbitan fatty acid esters, polyoxyalkylene sorbitan fatty acid esters, sorbit fatty acid esters, polyoxyalkylene sorbit fatty acid esters and lecithin.
(6) The solid adhesive composition as described in the above item (1) or (4), wherein the waxes have a content of 0.1 to 15% by weight based on the total amount of the composition.
(7) The solid adhesive composition as described in the above item (2) or (5), wherein the substance absorbing moisture contained at least in the atmosphere and/or the adhesive composition to form an evaporation-inhibiting film has a content of 0.01 to 10% by weight based on the total amount of the composition.
(8) The solid adhesive composition as described in any of the above items (3) to (5), wherein a content ratio of the waxes to the substance absorbing moisture contained at least in the atmosphere and/or the adhesive composition to form an evaporation-inhibiting film is 1/1 to 100/1 in terms of a weight ratio, and the total content thereof is 0.1 to 10% by weight based on the total amount of the composition.